Heat convection and design of brake discs

Abstract

An evaluation method of heat convection from brake discs using analytical and experimental approaches is described. Brake discs may be wheel or axle mounted and either ventilated or solid. The majority of brake discs are the ventilated type because of the cooling effect of the fins. In this study, the cooling efficiency of ventilated discs was investigated through the basic equation for heat convection, brake tests and measurements of the flow volume through the fins.

It is concluded that a cooling rate parameter α [= (heat convection × convection area)/(specific heat × disc mass)] derived from the basic equation for heat convection can express the cooling efficiency of a disc. The parameter α can also be used to estimate the maximum temperature accumulated in a disc after several cycles of braking to a stop. As for the design of the brake discs, the heat convection area is more important than the thickness or number of fins. Also the air velocity through the fins should be taken into consideration.

Keywords

brake disc heat convection specific heat cooling efficiency stop braking railway brake fin

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